Electric control for liquid fuel burners



12,1932. E. y c E 1,853,444

ELECTRIC CONTROL FOR LIQUID FISEL BURNERS Filed D 1925 4 Sheets-Sheet 1 IN V EN TOR.

' I lRA EMCHBE BY 7k ATTORNEYS.

April 12, 1932. l. E. M CABE 1,353,444

V ELECTRIC CONTROL FOR LIQUID FUEL BURNERS Filed Decf6, 1926 1 4 e tseet 2 INVENTOR. IRA 5 MCC'HBE' I 'ZTTORNEYS.

April 12, 1932. E. MCCABE 4 ELEcTRI CONTROL FOR LIQUID FUEL BURNERS Filed Dec. 6 1926 4 Sheets-Sheet I5 IN VEN TOR.

lRfl awe/v5: BY i ,4 M

ATTORNEYS.

April 12, 1932. l. E. cABE j 1,353,444

ELECTRIC CONTROL FOR LIQUID FUEL BURNERS 7 Filed Dec. 6,192 48heets-Sheet 4 BY X9 2? Patented Apr. 12, 1932 PATENT OFFICE,

IRA E. MCCABE, OF CHICAGO, ILLINOIS nLEc'raIc coN'raoL non LIQUID FUEL BURNEBS Application filed December 6, 1926, Seria1 No. 153,021.

This invention relates to improvements in electric controlling devices and more particularly to an electric control system for an automatically operated liquid fuel burner 53 for domestic heating purposes.

In devices of this character an electric motor is provided for driving the oil and air supply means and an electric ignition provided for igniting the flame when the burner is to be operated. A room thermostat is usually employed to open and close the motor circuit in accordance with the temperature desired to be maintained and when a hot Water or steam heating system is to be operated by the oil burner, a boiler or pressure control is also included in the motor circuit to discontinue the operation of the motor when the temperature or pressure within the boiler nears the danger point. In all devices of the character described it is also desirable to provide an additional safety means which should the burner flame fail to ignite upon the initial starting of the motor or should fail or become extinguished after ignition and during the operation of the motor thereafter, will operate to break the motor circuit. It is also desirable that such a safety device also operate to close the ignition circuit upon the initial operation of the motor and after the flame has been ignited to break the ignition circuit.

It is an object of this invention to provide an electric control system of the above type including the safety feature just described.

In-the drawings:

Figure 1 is a View in side elevation of a liquid fuel burner as applied to a domestic heating plant, illustrated in section and with parts broken away, to which this invention has been applied, showing the various control devices in elevation and the wiring in diagram? Figure 2 is a top plan view, partly in section, illustrating the application of the liquid fuel burner to the heater and part of the improved control system as applied thereto.

Figure 3 is aview in diagram illustrating the wiring as connected to the controls and safety device.

Figure 4 is an enlarged detail view in elevation of the safety device and indicating the wiring employed therewith in diagram.

Referring to Figure 1 of'the drawings illustrating an embodiment of this invention,

a domestic oil burner operated by an electric motor M is shown in connection with a domes tic heating plant having a boiler control or pressure control B adapted to be connected in circuit with the motor M and a room thermostat T. The safety device'comprises an elec- 6o trically actuated switch mechanism, shown in the switch box casing 1, electrically connected with an ignition device 2a and a lightcontrolled switch contained in casing 2 extending at one side of the burner mechanism and provided withan opening through which the burner flame isv'isible. n Figures 1, 3, and 4 the parts are shown with the electrically-actuated switch mechanism in the switch box 1 in the position assumed when the motor circuit has been broken by the opening of the hand-switch S and with the boiler control B and room thermostat T in closed positions.

The electrically actuated switch mechanism in the switch box casing 1 comprises a, panel P supporting six binding posts upon the back of the casing, two parallel arranged mercury tube switches 3 and 4 carried upon a support rotatably mounted on a pivot pin 5 extending from the back of the casing, and a solenoid 6 having a core 7 adapted to engage an arm 8 extending from the switch tube support, which, upon movement of the core in and out of the solenoid will tilt the switch tube support about its pivot 5. Mercury switch tube 3 is provided with four terminals arranged in pairs adjacent each end of the switch tube and switch tube 4. is provided with three terminals, one at each end and one in the center, so that when tilted in one direction, the mercury ineach tube will close the circuit through each pair of terminals adjacent the lower end of the switch and when tilted in the opposite direction will break the circuit through said pairs of terminals and close the circuit through the other pairs of terminals in the opposite ends of the switch before the circuit is broken between the first pair.

The six binding posts on panel P are connected by flexible leads to the switch tubes 3 and 4 and solenoid 6, in the following manner. Binding post 10 is connected by lead a to left hand terminal of lower switch tube 4; binding post 11 by lead I) to left hand terminal of upper switch tube 3; binding post 12 by lead 0 to the other terminal of left hand pair and by lead d to the inner terminal of the right hand pair in upper switch tube 3; binding post 13 by lead g to the intermediate terminal of the lower switch tube 4; binding post 143 by lead e to the other extreme right hand terminal at'the right of switch tube 3; and binding post 15 by lead f to the extreme right hand terminal in the lower switch tube 4. The solenoid winding is connected at one end by lead g to binding post 13. The other end of the solenoid winding is connected by lead 72. to binding post 12. Binding post 13 is connected by a wire W to one terminal of the boiler control B, the other terminal of which is in series with the room thermostat T through wire X, and one lead -Y of the commercial circuit. The other leadZ of the commercial circuit is connected to binding post 16 of the light switch mounted in the casing 2, the other terminal 17 of which is connected by lead V to lead 18 connecting binding post 11 to one pole of the motor M, the other pole of which motor is connected by lead 19 to binding post 15. Binding-postlO is connected by lead 20 to the ignition device 2a which in turn is connected by lead 21 to a li ht producing element 22, the other end of wiich is connected by lead 23 to binding post/ 14 and lead Z. L,

The light switch in casing 2 comprises a device fully described in my prior co-pending application Serial No. 133,868, filed September 7, 1926, so that only the general construction and operation need be described herein. The binding posts 16 and 17 thereof are connected by leads 16a. and 17a to the two separated terminals of the switch which enter bulb 24 thereof and between which contact is made or broken by a mercury seal contained in the restricted portion 25 connecting the bulb 24 to the bulb 26, which latter bulb is formed of a. medium adapted to absorb the energy of light rays falling upon it to increase its temperature and thereby increase its internal pressure to move the mercury seal into contact with the said terminals, and upon the removal of the source of light to return the mercury seal to a position to break the contact between said terminals. As shown in Figure 2, the

bulbs 24 and 26 are arranged within a cylindrical casing 27 secured to casing 2 but separated from the interior thereof by a screen 28 of a medium adapted to transmit light rays of the visible spectrum but absorb the infra red rays that may fall upon it. The casing 27 on the other side is separated by a similar screen 29 from the light producing'element 22 which is carried in a casing 30 forming an exterior closure for cylindrical casing 27 The casing 2 is shown as being connected on the draft pipe or air conduit of the burner mechanism and is provided with an opening through which the light from the ignited burner flame may pass and fall upon bulb 26 of the light switch and also provided with another opening into the air conduit at a distance from the first opening and said latter opening is preferably provided with a defiector plate 31, extending within the air conduit which will direct air therefrom, when the burner mechanism is in operation, into casing 2 to create a draft that will prevent the possibility of smoke from the burner flame will pass through lead 9 to the intermediate terminal in lower switch 4, passing through the-mercury and lead a to binding post 10 and then through lead 20 to the ignition device 2a, which is here shown as a section of bared resistance wire which will become incandescent as the current passes therethrough, and leaving the ignition device, it passes through lead 21 to the light producing element 22, here shown as an electric lamp, causing pro duction of light therein, andfrom thence by the way of lead 23 to lead Z by which it is connected to the commercial line, as the binding post 14 to which it is also connected, is in an open circuit. After the light producing element 22 has been on long enough to cause the light-switch tomake contact, the current will pass from binding post 13 through lead 9" to one end of the winding of the solenoid 6, and from lead it to binding post 12 and through lead 0 to the lower end of switch tube 3, the mercury in which closes the circuit through its terminals so that the current passes through lead I) to binding post 11 and through lead 18 to lead V, to which it is connected, to the light switch. Lead 18 extends therebeyond to one pole of the motor, but the circuit therethrough and lead 19 to the bind- The solenoid 6 is through the left hand pairs of terminals and closes the circuits through the pairs of terminals in the right hand ends thereof. This action closes the circuit from W through binding post 13 and lead 9 through switch 4 and lead f to binding post 15 and from thence by lead 19 to motor M and from thence through lead 18, lead V,through the light switch and then by lead Z to the commercial line. The starting of the motor supplies fuel to the burner which will beignited by the ignition device 2a so that the light therefrom will maintain'the light switch closed as long as the flame burns. The tilting of the-mercury tube switches to close the circuits just described, will also a predetermined time after the starting of the motor break the connection from binding post 13 through leads 9 and a and thereby break the circuit through lead 20 whichis in series with the ignition device 2a and light producing element 22. Although the circuit through the solenoid 6 by way of the left hand terminals is opened when the mercury tube switch 3 is tilted, the right hand terminals are closed before the left hand ones are broken, in this case due to the provision of an excess amount of mercury in the tube 3, so that the current passes from binding post 13 through lead 9, winding of-solenoid 6, lead it to binding post 12, through-lead d, switch 3, lead e, binding post 14, and lead 23 passes through wire Z to the commercial line.

In the position just described, and during the normal operation of the burner mechanism, thelight switch is in the commercia circuit and in series with the motor. u

Should the burner flame fail for any reason, either upon the initial operation of the motor or during the normal operation of the burner mechanism, the light switch will operate to break the motor circuit, but the circuit through the solenoid is not broken so that the safety switch tubes remain in the position assumed during the normal operation of the burner and in this position the ignition device is inoperative. The burner mechanism cannot again operate as long as the room thermostat T is closed until the entire circuit is broken and again closed. This may be accomplished by operating the hand switch S or, if the thermostat T- was closed atthe time the light switch broke the motor circuit, the

manually opening and closing of the entire circuit through the thermostat would accomplish same results. manually opening and closing of the entire circuit should be sufficient for the solenoid 6 to become de-energized and the combined weights of the core 7 and arm 8 will then tilt safety switch tubes 3 and 4 to the position shown upon the drawings and first described. During the normal operation of the burner mechanism when the room reaches the temperature desired the room thermostat The time for thesame applies to the operation of the boiler or pressure control B.

While the bulbs 24 and 26 are shown with a screen interposed between the bulbs and the light producing element 22 on one side and between the bulbs and the opening of the casing 2- into the heater, it is to be understood that both of these screens 28 and 29 could be omitted, or either one of them could be omitted, without departing from the scope of this invention.

The mercury tube switch 4 is of commercial structure with the intermediate terminal in the form of a disc with perforations about its periphery whereby the flow of mercury in moving from one position to the other v is delayed so that when the room thermostat is closed the current passing through the safety switch mechanism in casing 1 will operate the ignition device when the motor starts for a predetermined time thereafter by means of the delay action of switch 4.

v While a room thermostat is preferably used to automatically control the operation of the burner, any other type of switch, either at the burner or at a distance therefrom, is contemplated as a part of. this invention.

What I claim is:

1. A fluid fuel burner mechanism having an electric motor for supplying fuel to the burner, acontrol system therefor comprising a light actuated switch controlling the motor, a light producing element positioned to illuminate said light switch to cause closing of the same, a hot wire igniter positioned to ignite the burner and in circuit with said light producing element, said light producing element and said igniter being constructed to become incandescent in the same time period.

light producing element and the burner flame,

said i-gniter being positioned to ignite the burner; said switching mechanism connecting, first; said igniter and light producing a light element to said power source and a circuit through said solenoid in series with the light switch and power source when said solenoid is deenergized, and second; disconnecting said igniter and light producing element from the'power source, closing a second circuit through said solenoid in series with said power source and closing a circuit through said motor in series with said light switch and power source when said solenoid is energizcd. IRA E. McCABE. 

